I. The Field of the Invention
The present invention relates generally to methods and devices for portable wet drilling waste treatment.
II. Background and Relevant Art
In drilling operations, a fluid commonly referred to as “mud” is circulated from the surface, downward through a drill pipe and out openings in the drill bit at the bottom of a borehole. The mud may include hydrocarbons, lubricants and other chemicals that assist in the drilling process. After exiting the drill bit at the bottom of the borehole, the mud along with other material from the borehole (often referred to collectively as “cuttings”), are pushed back upward through the borehole to the surface.
Once at the surface, the cuttings that are extracted from the borehole may be processed in order to separate the mud from the other material. The mud may then be recycled and sent back down the drill pipe, and the material that is separated from the mud may be collected into a separate area. Depending on the depth of the borehole and the location of the drill site, the material that is separated from the mud, which is commonly referred to as “sludge,” may include a mixture of different solids, such as stone, dirt, clay, and salt. Sludge may also include toxic materials like hydrocarbons, heavy metals, and naturally occurring radioactive material. Despite the separating process, it is also common for sludge to include nonsolid components, such as water, oil, mud, and other fluids. Sludge can be very difficult to handle with conventional equipment.
Untreated sludge should not be introduced directly back into the environment for a variety of reasons. For example, if the discarded sludge contains salt, plant life at or around an area where sludge is dumped may die. Further, if the sludge contains hydrocarbons, heavy metals or other toxic materials, these materials may leach into the ground and contaminate ground water. Many states have regulations that make it illegal to dump untreated sludge from a drill site into the environment.
Sludge from a drill site can be treated at the drill site. Conventional techniques for treating sludge near a drill site include digging a large pit into the ground near the drill site. The bottom and side walls of the pit may be lined with a thick plastic liner to prevent environmental contamination from the sludge. The sludge may then be deposited into the pit. A chemical that treats the sludge may then be added to the sludge pit and mixed into the sludge. Due to the size of the pits, trackhoe excavators are often used to mix the chemical into the sludge. The chemical mixed into the pool of sludge may convert the mixture into a solid, thereby rendering inert any potentially hazardous materials within the sludge.
This method for treating sludge is problematic for a number of different reasons. First, the space around a drill site is often limited. Depending on the depth and size of a borehole, there may not be sufficient space available in the immediate vicinity of a drill site to dig a pit large enough to deposit and treat sludge. Second, there is a significant potential for environmental contamination. It is not uncommon for a trackhoe operator to tear the plastic lining within a pit during the mixing process. If the plastic lining within the pit is torn, there is no barrier to keep the sludge from seeping into the ground. Third, mixing the chemical thoroughly into the sludge can be difficult. If not mixed thoroughly, some of the sludge may not be treated and may remain potentially hazardous to the environment. Further, if the sludge is not mixed completely or if an insufficient amount of or ineffective chemical is used to treat the sludge, the treated mixture may not solidify properly. There is a potential that a vehicle traveling over or a person walking across such a sludge pit may sink into the pit.
Finally, a pit containing untreated sludge can be a danger to birds and other animals that land on or wander into it. As untreated sludge sits in a pit, the solids may separate from the fluids. The solids settle to the bottom of the pit and the fluid collects at the surface. This fluid is often oily, containing hydrocarbons. Any bird or other animal that comes into contact with this fluid is likely to be harmed. Recognizing the significance of this problem, federal regulations exist that impose a fine on operators of drill sites for each animal that dies in a sludge pit.
Alternatively, sludge may be treated off-site. To treat sludge at an off-site location, the sludge may be collected into transportable containers. Often these containers are then taken by truck to a facility where the sludge is treated. Once treated, the sludge may be used as fill material back at the drill site or it can be discarded at a landfill.
As with on-site treatment of sludge, transporting sludge to an off-site facility for treatment is problematic for a number of different reasons. First, there is a significant potential for environmental contamination. Sludge can be spilled while being transferred from the drill site to the transportable container. In addition, there is a potential that the sludge can leak from the container while in transit to the treatment facility. Second, transporting sludge to an off-site facility requires significant resources, including fuel, time, and manpower. Sludge must be loaded into a container and unloaded at a treatment facility. Once treated, the material must be reloaded back onto a truck to either be returned to the drill site or taken to a landfill. Because of these dangers, there are federal regulations that limit the weight, volume, and physical condition of sludge that can be transported in one load by a single truck. There are also federal regulations that limit the amount of time that a licensed driver can drive in a single day. Compliance with these regulations often makes the transportation of sludge even more expensive. Finally, because the space around a drill site is limited, it can be difficult to get trucks into and away from the drill site. As the distance between the drill site and the trucks increases, the potential for a spill between the drill site and the truck also increases.
The aforementioned problems relating to sludge that are encountered in the drilling industry are also encountered in a number of other industries. Indeed, waste material (including sludge) is a common byproduct that exists in many different industries. As in drilling operations, waste material in other industries is often in need of treatment before it can be discarded. Large vacuum trucks are often used to collect waste material. Because vacuum trucks are not generally equipped to treat the waste material, once the vacuum truck is full, the truck must transport the waste material to a specialized facility for treatment. The waste material may be removed from the vacuum truck and treated by the facility. Once the waste material has been treated, it may be loaded into another truck or trailer for final disposal. As explained previously, this method for collecting and treating waste materials is problematic.